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0d33a981ec
- fix some broken hyperlinks - add additional hyperlinks to references to external documents - reformat some paragraphs to keep lines under 80 characters - unify the enumeration style between different parts of the documentation - fix spelling/grammar mistakes - extend the copyright notice in README.md to be the same as the one in COPYING.BSD Signed-off-by: Karsten Merker <merker@debian.org> Reviewed-by: Atish Patra <atish.patra@wdc.com>
41 lines
1.6 KiB
Markdown
41 lines
1.6 KiB
Markdown
U-Boot as a payload to OpenSBI
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==============================
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[U-Boot](https://www.denx.de/wiki/U-Boot) is an open-source primary boot loader.
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It can be used as first and/or second stage boot loader in an embedded
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environment. In the context of OpenSBI, U-Boot can be specified as a payload to
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the OpenSBI firmware, becoming the boot stage following the OpenSBI firmware
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execution.
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The current stable upstream code of U-Boot does not yet include all patches
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necessary to fully support OpenSBI. To use U-Boot as an OpenSBI payload, the
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following out-of-tree patch series must be applied to the upstream U-Boot source
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code:
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HiFive Unleashed support for U-Boot
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https://lists.denx.de/pipermail/u-boot/2019-February/358058.html
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This patch series enables a single CPU to execute U-Boot. As a result, the next
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stage boot code such as a Linux kernel can also only execute on a single CPU.
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U-Boot SMP support for RISC-V can be enabled with the following additional
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patches:
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https://lists.denx.de/pipermail/u-boot/2019-February/358393.html
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Building and Generating U-Boot images
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=====================================
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Please refer to the U-Boot build documentation for detailed instructions on
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how to build U-Boot images.
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Once U-Boot images are built, the Linux kernel image needs to be converted
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into a format that U-Boot understands:
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```
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<uboot-dir>/tools/mkimage -A riscv -O linux -T kernel -C none -a 0x80200000 -e 0x80200000 -n Linux -d \
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<linux_build_directory>arch/riscv/boot/Image \
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<linux_build_directory>/arch/riscv/boot/uImage
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```
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Copy the uImage to your tftpboot server path if network boot is required.
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